They discover where the high-energy particles that threaten satellites, astronauts and airplanes come from


Astrophysicists at Columbia University (United States) have discovered how and when high-energy particles in space are formed, as published in ‘The Astrophysical Journal Letters’.

For decades, scientists have tried to solve the problem of high-energy particles that unpredictably bombard Earth and objects outside Earth’s atmosphere with radiation that can endanger the lives of astronauts and destroy electronic equipment. of the satellites.

These eruptions can even unleash radiation showers strong enough to hit passengers on planes flying over the North Pole. Despite the efforts of scientists, it remains difficult to identify a clear pattern of how and when the eruptions occur.

Authors Luca Comisso and Lorenzo Sironi, from the Department of Astronomy and Columbia Astrophysics Laboratory, have used supercomputers for the first time to simulate when and how high-energy particles are born in turbulent environments like that of the Sun’s atmosphere. This research paves the way to more accurately predict when the dangerous bursts of these particles will occur.

“This exciting new research will allow us to better predict the origin of solar energetic particles and improve forecasting models for space weather events, a key goal of NASA and other space agencies and governments around the world,” said Comisso.

Over the next two years, he adds, NASA’s Parker Solar Probe, the closest spacecraft to the sun, will be able to validate the paper’s conclusions by directly observing the predicted distribution of high-energy particles being generated in the sun’s outer atmosphere. .

In their paper, Comisso and Sironi show that magnetic fields in the sun’s outer atmosphere can accelerate ions and electrons to speeds close to the speed of light. The outer atmosphere of the Sun and other stars is made up of particles in a plasma state, a highly turbulent state distinct from liquid, gas, and solid states.

Scientists have long believed that the sun’s plasma generates high-energy particles. But plasma particles move so erratically and unpredictably that until now they have not been able to fully demonstrate how and when this happens.

Using supercomputers at Columbia, NASA, and the National Center for Energy Science Research, Comisso and Sironi created computer simulations that show the exact motions of electrons and ions in solar plasma. These simulations mimic the atmospheric conditions of the sun and provide the most extensive data gathered to date on how and when high-energy particles form.

The research provides answers to questions that scientists have been investigating for at least 70 years: In 1949, physicist Enrico Fermi began investigating the magnetic fields of outer space as a potential source of high-energy particles (which he called cosmic rays) that are observed entering the Earth’s atmosphere. Since then, scientists have suspected that solar plasma is a major source of these particles, but definitively proving it has been difficult.

Comisso and Sironi’s research, conducted with support from NASA and the National Science Foundation, has implications beyond our own solar system. Most of the observable matter in the universe is in the plasma state.

Understanding how some of the particles that make up plasma can be accelerated to high-energy levels is an important new area of ​​research, as energetic particles are routinely observed not only around the sun, but also in other environments in the universe. including the surroundings of black holes and neutron stars.

Although Comisso and Sironi’s new work focuses on the sun, more simulations could be done in other contexts to understand how and when distant stars, black holes, and other entities in the universe will generate their own bursts of energy.

“Our results focus on the sun, but can also be considered a starting point to better understand how high-energy particles are produced in more distant stars and around black holes,” Comisso says. “We have only scratched the surface.” what supercomputer simulations can tell us about how these particles are born throughout the universe.”

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